[PATCH v7 6/8] i2c: amd-asf: Add routine to handle the ASF slave process

Shyam Sundar S K
2024-09-23T08:05:40Z

Add support for handling ASF slave process events as described in the AMD
ASF databook. This involves implementing the correct programming sequence
to manage each ASF packet appropriately.

Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Co-developed-by: Sanket Goswami <Sanket.Goswami@amd.com>
Signed-off-by: Sanket Goswami <Sanket.Goswami@amd.com>
Signed-off-by: Shyam Sundar S K <Shyam-sundar.S-k@amd.com>
---
drivers/i2c/busses/i2c-amd-asf-plat.c | 101 ++++++++++++++++++++++++++
1 file changed, 101 insertions(+)

diff --git a/drivers/i2c/busses/i2c-amd-asf-plat.c b/drivers/i2c/busses/i2c-amd-asf-plat.c
index 216b194202ba..fa6db99a8fe5 100644
--- a/drivers/i2c/busses/i2c-amd-asf-plat.c
+++ b/drivers/i2c/busses/i2c-amd-asf-plat.c
@@ -11,6 +11,7 @@

#include <linux/bitops.h>
#include <linux/device.h>
+#include <linux/devm-helpers.h>
#include <linux/errno.h>
#include <linux/gfp_types.h>
#include <linux/i2c.h>
@@ -33,21 +34,90 @@
#define ASF_CLK_EN 17

/* ASF address offsets */
+#define ASFINDEX (0x07 + piix4_smba)
#define ASFLISADDR (0x09 + piix4_smba)
#define ASFSTA (0x0A + piix4_smba)
#define ASFSLVSTA (0x0D + piix4_smba)
+#define ASFDATARWPTR (0x11 + piix4_smba)
+#define ASFSETDATARDPTR (0x12 + piix4_smba)
#define ASFDATABNKSEL (0x13 + piix4_smba)
#define ASFSLVEN (0x15 + piix4_smba)

#define ASF_BLOCK_MAX_BYTES 72
+#define ASF_ERROR_STATUS GENMASK(3, 1)

struct amd_asf_dev {
struct i2c_adapter adap;
struct i2c_client *target;
+ struct delayed_work work_buf;
struct sb800_mmio_cfg mmio_cfg;
struct resource *port_addr;
};

+static void amd_asf_process_target(struct work_struct *work)
+{
+ struct amd_asf_dev *dev = container_of(work, struct amd_asf_dev, work_buf.work);
+ unsigned short piix4_smba = dev->port_addr->start;
+ u8 data[ASF_BLOCK_MAX_BYTES];
+ u8 bank, reg, cmd;
+ u8 len, idx, val;
+
+ /* Read target status register */
+ reg = inb_p(ASFSLVSTA);
+
+ /* Check if no error bits are set in target status register */
+ if (reg & ASF_ERROR_STATUS) {
+ /* Set bank as full */
+ cmd = 0;
+ reg |= GENMASK(3, 2);
+ outb_p(reg, ASFDATABNKSEL);
+ } else {
+ /* Read data bank */
+ reg = inb_p(ASFDATABNKSEL);
+ bank = (reg & BIT(3)) ? 1 : 0;
+
+ /* Set read data bank */
+ if (bank) {
+ reg |= BIT(4);
+ reg &= ~BIT(3);
+ } else {
+ reg &= ~BIT(4);
+ reg &= ~BIT(2);
+ }
+
+ /* Read command register */
+ outb_p(reg, ASFDATABNKSEL);
+ cmd = inb_p(ASFINDEX);
+ len = inb_p(ASFDATARWPTR);
+ for (idx = 0; idx < len; idx++)
+ data[idx] = inb_p(ASFINDEX);
+
+ /* Clear data bank status */
+ if (bank) {
+ reg |= BIT(3);
+ outb_p(reg, ASFDATABNKSEL);
+ } else {
+ reg |= BIT(2);
+ outb_p(reg, ASFDATABNKSEL);
+ }
+ }
+
+ outb_p(0, ASFSETDATARDPTR);
+ if (cmd & BIT(0))
+ return;
+
+ /*
+ * Although i2c_slave_event() returns an appropriate error code, we
+ * don't check it here because we're operating in the workqueue context.
+ */
+ i2c_slave_event(dev->target, I2C_SLAVE_WRITE_REQUESTED, &val);
+ for (idx = 0; idx < len; idx++) {
+ val = data[idx];
+ i2c_slave_event(dev->target, I2C_SLAVE_WRITE_RECEIVED, &val);
+ }
+ i2c_slave_event(dev->target, I2C_SLAVE_STOP, &val);
+}
+
static void amd_asf_update_ioport_target(unsigned short piix4_smba, u8 bit,
unsigned long offset, bool set)
{
@@ -207,10 +277,29 @@ static const struct i2c_algorithm amd_asf_smbus_algorithm = {
.functionality = amd_asf_func,
};

+static irqreturn_t amd_asf_irq_handler(int irq, void *ptr)
+{
+ struct amd_asf_dev *dev = ptr;
+ unsigned short piix4_smba = dev->port_addr->start;
+ u8 target_int = inb_p(ASFSTA);
+
+ if (target_int & BIT(6)) {
+ /* Target Interrupt */
+ outb_p(target_int | BIT(6), ASFSTA);
+ schedule_delayed_work(&dev->work_buf, HZ);
+ } else {
+ /* Controller Interrupt */
+ amd_asf_update_ioport_target(piix4_smba, ASF_SLV_INTR, SMBHSTSTS, true);
+ }
+
+ return IRQ_HANDLED;
+}
+
static int amd_asf_probe(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
struct amd_asf_dev *asf_dev;
+ int ret, irq;

asf_dev = devm_kzalloc(dev, sizeof(*asf_dev), GFP_KERNEL);
if (!asf_dev)
@@ -221,6 +310,18 @@ static int amd_asf_probe(struct platform_device *pdev)
if (!asf_dev->port_addr)
return dev_err_probe(dev, -EINVAL, "missing IO resources\n");

+ ret = devm_delayed_work_autocancel(dev, &asf_dev->work_buf, amd_asf_process_target);
+ if (ret)
+ return dev_err_probe(dev, ret, "failed to create work queue\n");
+
+ irq = platform_get_irq(pdev, 0);
+ if (irq < 0)
+ return dev_err_probe(dev, irq, "missing IRQ resources\n");
+
+ ret = devm_request_irq(dev, irq, amd_asf_irq_handler, IRQF_SHARED, "amd_asf", asf_dev);
+ if (ret)
+ return dev_err_probe(dev, ret, "Unable to request irq: %d for use\n", irq);
+
asf_dev->adap.owner = THIS_MODULE;
asf_dev->adap.algo = &amd_asf_smbus_algorithm;
asf_dev->adap.dev.parent = &pdev->dev;
--
2.25.1